The present invention relates to wristwatches. It concerns, more particularly, watches formed of a case provided with a slide-way and a wristlet engaged in the slide-way and able to move in translation. Watches of this type are known, for example, from European Patent No. 0 264 874, GB Patent No. 2 217 577, U.S. Pat. No. 5,068,840 or Belgian Patent No. 545 237. Such a solution allows a wristlet with a single strand to be made. Moreover, the case may be moved on the wristlet, so as to place it in a position chosen by the person wearing the watch, in particular to facilitate reading the time.
In these watches, the wristlet or watch strap is made of a flexible material, generally leather or fabric. This may result in rapid wear, due to the friction of the slide-way on the wristlet. However, if the case can move too easily along the wristlet, it is liable to move when worn, frequently obliging the person wearing it to put it back in place.
The main object of the invention is to overcome these drawbacks. This object is achieved by the watch defined by claim 1.
Particularly good results have been obtained using a strap made of a knitted thread, in particular a metal thread, for example defining a so-called Milanese structure.
Tests have shown that the two rolls forming the wristlet can be obtained by permanently deforming the strap formed by bending, the longitudinal edges of the latter being in contact with its median portion. It is thus not necessary to weld or bond the edges of the strap to guarantee the shape of the wristlet. Moreover, the structure thereby obtained has great flexibility and rounded edges, making it more comfortable for the person wearing it.
In the watch according to the invention, it is desirable for the wristlet to be easily moved in the slide-way when it is in an extended position, so as to be able to position it quickly. When the watch is being worn, however, it is preferable for the case to be able to slide only insofar as the person wearing it wishes. This is why, in an advantageous manner, the wristlet and the case are arranged so that, in the extended position, the wristlet can slide freely on the case, while in the bent position, the case can only be moved on the wristlet via the action of force which is higher the lower the radius of curvature of the wristlet.
This feature may be obtained when the rolls define a resilient structure which forms rough portions intended to co-operate with the walls of the slide-way when the wristlet is bent. Thus, the rough portions, by co-operating with the walls of the slide-way, assure proper positioning of the case, without thereby blocking it.
In known watches, the slide-way is formed of loops which define a rectangular opening delimited by walls on four sides. With such a structure, applied to a watch in which friction is defined by the rough portions of the wristlet on the walls of the slide-way, the latter is liable to prevent any movement of the watch when it is being worn. This is why, in an advantageous manner, the case is of generally parallelepiped shape, including in particular two large faces and two small faces, in which:
one of the large faces, the top one, is provided with a crystal through which the time can be read;
the other large face, the bottom one, forms one of the walls of the slide-way, and
the two small faces extend beyond the large bottom face and form claws which constitute, with the bottom face, the walls of the slide-way.
In order to assure comfortable wear, aesthetic appearance and longevity, both the wristlet and the case are made of metal.
The invention also concerns a wristlet, in particular a watch wristlet, according to claim 10.